This invention relates generally to the field of solar energy collection systems and in particular to an improved unitary coextruded solar collector panel of the type having an upper, heat insulating region, and a lower, heat absorbing region.
Recent realizations that alternative energy sources to fossil fuels must be developed have caused substantial efforts to be made in developing a commercially acceptable solar energy collection system. An essential component of any solar energy collection system being the solar collector panel, a substantial amount of effort has been expended in the development of this element of the system.
Initial efforts to develop a useful solar collector panel often resulted in heavy, cumbersome structures involving the use of several, often incompatible, construction materials. This problem was particularly acute in the design of an acceptable flat plate type solar collector panel.
The flat plate type collector panel is generally more compatible with large structures, such as homes or offices, lending themselves well to the solar heating of air or water for use in the home or office, of water for distillation purposes, and even of water for use in heating a swimming pool. This compatibility results from the existence on all buildings of large flat areas, such as the roof or walls, upon which such flat plate type collector panels may be mounted.
Although well suited for use in connection with a building, flat plate type collector panels had not yet found wide commercial acceptance for various reasons. Moreover, the cost of producing an efficient and workable collector panel often far outweighed its return, seriously limiting acceptance of such collectors by the public.
My patent application, Ser. No. 645,648 now U.S. Pat. No. 4,114,597, which is hereby incorporated by reference herein, discloses a flat plate type solar collector panel which serves to eliminate the above-mentioned drawbacks thus enabling production of a commercially acceptable solar thermal energy collection system. This is accomplished by providing a solar collector panel which is unitary in construction and which is capable of being produced in long, lightweight and continuous sections. In this manner entire portions of a structure may be covered with a series of such panels thereby enabling the conversion of sufficient amounts of solar thermal energy to provide for the heating needs of a consumer.
The unitary collector panels disclosed are produced by coextruding a selected combination of synthetic thermoplastics into long panels having heat insulating and heat absorbing layers along their entire length. In this manner the previously required combination of construction materials is replaced by a single unit requiring no individual construction or separate parts. The resulting units are lightweight which permits easy installation and also permits large surface areas to be completely utilized without requiring substantial shoring of the underlying structural members. The unit is also capable of being produced in large sizes and quantities, decreasing both the cost of such units as well as the costs of installation and labor.
Although the unitary solar collector panels above described are well suited to solving the problems presented in converting solar energy into heat, it has been found that certain aspects of those collector panels are capable of improvement, further enhancing the utility and potential for public acceptance of the resulting solar energy collection system.
One such aspect concerns the particular nature and configuration of the ribs used to separate the heat insulating region and the heat absorbing region into channels through which a fluid may be uniformly maintained or circulated.
For example, it has been found that unitary collector panels exhibit a certain degree of radiation and convection losses from the heat insulating region. These losses can be reduced by suitably modifying the ribs used to form the channels of that region.
Also, the heat absorbing region of such collector panels is capable of certain improvements. Modifications to the ribs which form that region can enhance heat conduction from the heat absorbing region to the fluid circulated therethrough, and can reduce the bowing of collector panels out of their planar configuration, which has been encountered in certain environments.